1. Field of the Invention
This invention relates to a durable toothbrush head which is effective for cleaning and polishing teeth, and massaging and stimulating the gums, without injury to the hard or soft tissues.
Conventional toothbrushes with nylon bristles have been used since the 1940's. Despite manufacturer's numerous attempts to improve nylon bristles, they continue to exhibit the same disadvantages as conventional toothbrushes. These disadvantages include: (1) rapid permanent deformation (matting and tapering of the bristles) of the brushing structure resulting in inefficient cleaning and limited toothbrush life: (2) poor polishing (inadequate coefficient of friction and surface area): (3) abrasion to hard and soft tissues: and (4) difficulty in cleaning and drying bristles and tuft retention apertures resulting in compromised hygiene and consequent bacterial/fungal growth.
A person generally uses his or her toothbrush for up to six months. However, for many brush heads, the effect of permanent deformation is manifest by a drop in the ability to remove plaque after only about three weeks of use. In areas where the tooth surface becomes more difficult to reach, such as lingual surfaces, the loss of effectiveness is greater. Both bristle matting and bristle tapering substantially reduce the ability of the brush to remove plaque. Studies have shown that toothbrushes with considerable wear were 50-100% less effective in removing plaque than new toothbrushes. Brush conditions deteriorate with length of use; however, length of use is not determinative in the amount of matting and tapering present. A brush resistant to matting would have markedly superior durability.
Studies have shown that thermoplastic elastomers manifest a polishing of enamel and cementum while the nylon head tends to track on the enamel and cementum and scratch the surface of the tooth. Additionally, thermoplastic elastomeric materials are resistant to fatigue, and thus, to bristle matting and tapering.
One study found that the only successful method for sterilization of a toothbrush is heating in a microwave oven. However, this method distorts nylon bristles so that it is not feasible for a nylon toothbrush.